A pair of mountain lion cubs killed by game wardens in Half Moon Bay on Dec. 1 turned out to be far smaller and younger than first reported, an apologetic state Department of Fish and Game official reported.

Originally described as 10 months old and 30 pounds, a necropsy of the two females found that they were 4 months old, weighing 13 and 14 pounds, a little bigger than house cats. Their stomachs were empty, and wildlife officials said the apparently orphaned cubs probably would not have survived in the wild.

"With the necropsy reports, I now realize these animals were smaller than assumed," Charlton Bonam, the department's director, said in a statement Friday. "I regret this unfortunate incident in Half Moon Bay for all involved."

The cubs were spotted hunkering under a backyard deck during a driving rainstorm. With the lions only a block from downtown Half Moon Bay, wardens decided not to attempt to drug the cubs, but fatally shot them both.

"In a perfect world, we would have had further non-lethal options available," Tony Warrington, the department's assistant chief, said in a statement. "Our trained wardens work in extraordinarily difficult circumstances every day and this day was no exception."

The shootings drew complaints from wildlife groups.

"We need to ask the department ... to consider non-lethal action and to network with outside experts for advice and assistance when appropriate," said Rebecca Dmytryk of Wildlife Emergency Services, an animal rescue group.